This should fix several issues with odd dimensions inputs.
lut, vflip, pad and crop video filters also need to be checked for such
issues. It's possible sws is also affected.
Rely on generic utilities for computing each plane linesize.
In particular, add support to NV12/21 formats and avoid use of
PIX_FMT_PLANAR pixdesc flag, whose semantics is questionable.
It also fixes various crashes.